RU1810711C - Method of laying underwater pipe line - Google Patents

Abstract

SUMMARY OF THE INVENTION: a pipeline (TP) is led to the head in the transition target, equipped with flows and laid at the bottom of the reservoir with the formation of a 3-fold bend of the TP with water. TP is equipped with pontoons at the settlement site. Combine the gulf of water in the HTP and the movement of pontoons along it. The pontoons are located at a depth determined depending on the depths of the location of the middle of the pontoons and the reservoir. The length of the design section-TP is determined depending on the bending stiffness of the TP and the negative buoyancy of the TP. 2 ill.

Description

mobile devices 3 are mounted on 2, made, for example, in the form of a carriage frame supported from below by a pipeline. Unloading means, pontoons 4, are connected to the mobile devices 3, and the mobile devices are connected by cables 5.-.

The number of mobile devices 3 and the carrying capacity of the pontoons 4 are determined by calculating from the condition that they provide the necessary reduction of loads on the lower section of the S-shaped curve (negative buoyancy) required by the strength criterion.

After installing the mobile devices 3 with the pontoons 4 in the initial position (Fig. 1), the pipeline begins to fill with water, while it sinks to the bottom along an S-shaped curve. At the same time as the pipeline is filled with water, the pontoons 4 are moved with a towing winch 6 installed on the shore or on the ship, by means of a cable 7 (Fig. 2). In this case, the pontoons 4 are supported during the immersion process at a depth determined from relation (1), and the length of the calculated section of the pipeline equipped with pontoons 4 is determined from dependence (2).

The position of the pontoons 4 during the installation process is controlled, for example, using a cable 8 with a float 9. Depending on the position of the float on the surface of the reservoir, adjustments are made to the movement of the pontoons 4 and filling the pipeline with water.

When the conditions of relations (1) and (2) are fulfilled during laying, the unloading means are located in the zone of maximum curvature of the lower section of the S-shaped curve. In this case, the effect of straightening the bending curve from lowering the loads will be greatest and, therefore, the maximum depth of laying will be maximized .

For installation, pipelines with a diameter of 1020 mm, a wall thickness of 12 mm, have 0

5

0

5

0

5

0

With a negative buoyancy of 230 kg / m and a positive buoyancy of 570 kg / m, to a depth of 12 m, for example, three mobile devices with unloading connections - pontoons with a carrying capacity of 7 tons each are used. Pontoons are installed on a segment of a 20 m long pipeline. The pipeline is filled with water and pontoons are moved along it, supporting the middle one at a depth of 8 m (in accordance with ratios 1 and 2). In this case, the position of the pontoons is monitored. Near the opposite shore, at a depth of about 3 m, the pontoons are dismantled and hang up without them already.

When laying by the proposed method, a depth of 12 m is reached with a permissible bending stress of 2500 kg / cm2. The proposed method allows to increase the laying depth by more than 2 times.

Claims (1)

SUMMARY OF THE INVENTION A method of laying a submarine pipeline, which involves flooding it into the transition target, equipping it with pontoons and laying it on the bottom of the reservoir with the formation of an S-shaped bend of the pipeline by filling it with water, characterized in that the pipeline is equipped with movable pontoons in the design section, while combining water filling the pipeline and moving pontoons along it, the latter being located at a depth h (0.6-0.7) H. where h is the depth of the middle of the pontoon section; . H is the depth of the reservoir, m, and the length I of the design pipeline equipped with mobile pontoons is determined from the dependence ; 0.7 where E is the bending rigidity of the pipeline, kgm2; p - negative buoyancy of the pipeline, kg / m g FIG. I